ANATOMY OF THE KNEE-JOINT. 229 



from one auother by the attachment of the mucous ligament, 

 and which, in the nearly extended state of the joint, is pulled 

 back into the angular space between the condyles of the femur 

 and the tibial aspect of the articulation by tlie traction of the 

 mucous ligament ; and, in the flexed condition, is forced back- 

 wards by the pressure of the atmosphere. 



The supra-patellar pad is adapted to a deep and charac- 

 teristic notch, which exists between the upper end of the 

 patella and the tendon of the quadriceps extensor. This would 

 appear to adapt the tendon to the bone in the varied antero- 

 posterior angular positions of the two parts during action. 



The lateral patellar pad is the pouch-like fold which 

 sheathes the internal longitudinal facet of the patella. 



The great and the supra-trochlear pads are situated, the 

 former at the upper and outer part of the great cul-de-sac of 

 the synovial membrane ; the latter, a larger external and 

 smaller internal, towards the upper part of the outer face of the 

 trochlea. These fill up the space between the patella and 

 the fore part of the femur above the trochlea in complete 

 extension. 



I may conclude by adverting shortly to the remarkable 

 facetted configuration of the articular cartilages of the knee- 

 joint, a structure which has hitherto escaped notice. In 

 a previous part of this lecture the facets of the patella have 

 been described ; which bone, from the variable projections of 

 these facets, exhibits sometimes a concavity, sometimes a 

 convexity, and occasionally a flat profile. 



On the surface of the tibial condyles the following facets 

 may be demonstrated : — a semilunar facet on each condyle, 

 corresponding to the under surfaces of the semilunar fibro- 

 cartilages, and separated by faint but distinct blunt ridge.s 

 from a central femoral facet on each condyle, the latter in 

 contact with the femoral cartilage. 



On the femur, in addition to tho trochlea separated from 



